Lorraine E. Levitt Katz

Insulin-like growth factor binding protein (IGFBP) proteases: functional regulators of cell growth.

The IGFBP proteases were first described in pregnancy serum as a proteolytic activity against IGFBP-3. Since then, IGFBP proteases have been described in many other clinical situations, in various body fluids, and have been shown to cleave IGFBP-2 to -6 with varying specificity. The molecular nature of some of these proteases is being unraveled and three classes of IGFBP proteases have been recognized. These include kallikreins, cathepsins and matrix metalloproteinases (MMPs). We utilized two cellular systems to demonstrate the significance of IGFBP proteases in cellular growth regulation. In primary cultures of prostatic cells, we have shown that prostate-specific antigen (PSA) has the ability to enhance IGF mitogenic action by reducing the effects of IGFBPs. Similar kallikreins such as gamma nerve growth factor (NGF) share this activity. Within the prostatic milieu, we have also demonstrated epithelial production of the acid-activated IGFBP protease, cathepsin D, and its secretion into seminal plasma, as well as the serum of patients with prostate malignancy. We have also identified MMPs in prostatic cells and fluids. Using cultured airway smooth muscle (ASM) cells, we have demonstrated the synergism between IGFs and inflammatory agents in mediating ASM cell proliferation. Examination of this phenomenon revealed that these agents (e.g. leukotriene D4 and interleukin1-beta) induce the secretion of an IGFBP protease which cleaves the IGFBPs secreted by ASM cells, allowing IGFs to stimulate proliferation. Using several methods, including immunoblotting and immunodepletion techniques, we have identified this protease as MMP-1. These two pathophysiological systems demonstrate the importance of IGFBP proteases as autocrine paracrine growth regulators. Furthermore, IGFBP proteases may be critical elements in malignant and benign proliferative diseases, including prostate cancer and the ASM hyperplasia of long-standing asthma.

Lipid and inflammatory cardiovascular risk worsens over 3 years in youth with type 2 diabetes

OBJECTIVE Type 2 diabetes increases cardiovascular risk. We examined lipid profiles and inflammatory markers in 699 youth with recent-onset type 2 diabetes in the TODAY clinical trial and compared changes across treatment groups: metformin alone (M), metformin plus rosiglitazone (M+R), and metformin plus intensive lifestyle program (M+L). RESEARCH DESIGN AND METHODS Multiethnic youth with type 2 diabetes received M, M+R, or M+L. Statin drugs were begun for LDL cholesterol (LDL) ≥130 mg/dL or triglycerides ≥300 mg/dL. Lipids, apolipoprotein B (apoB), LDL particle size, high-sensitivity c-reactive protein (hsCRP), homocysteine, plasminogen activator inhibitor-1 (PAI-1), and HbA1c were measured over 36 months or until loss of glycemic control. RESULTS LDL, apoB, triglycerides, and non-HDL cholesterol (HDL) rose over 12 months and then stabilized over the next 24 months. Participants with LDL ≥130 mg/dL or using LDL-lowering therapy increased from 4.5 to 10.7% over 36 months, while 55.9% remained at LDL goal (<100 mg/dL) over that time. Treatment group did not impact LDL, apoB, or non-HDL. Small dense LDL (particle size, ≤0.263 relative flotation rate) was most common in M. Triglycerides were lower in M+L than M, and M+L attenuated the negative effect of hyperglycemia on triglycerides and HDL in females. hsCRP, PAI-1, and homocysteine increased over time. However, hsCRP was lower in M+R compared with M or M+L. CONCLUSIONS Dyslipidemia and chronic inflammation were common in youth with type 2 diabetes and worsened over time. Diabetes treatment, despite some treatment group differences in lipid and inflammatory marker change over time, is generally inadequate to control this worsening risk.

Metabolic effects of obesity causing disease in childhood.

Purpose of reviewChildhood obesity is rising to epidemic proportions throughout the world, and much emphasis has been placed on the long-term consequences that can result later, in adulthood. This article reviews the metabolic consequences of obesity that can manifest as disease during the childhood years. Recent findingsObese children suffer from many disease processes once thought to affect only adults. They can have type 2 diabetes mellitus, and potentially early β cell failure with rapid progression to an insulin requirement. There is a high prevalence of fatty liver disease in obese children, and complications such as steatohepatitis and even cirrhosis can develop during childhood. Visceral fat has been shown to have many different properties than subcutaneous fat, and children with central adiposity can develop the metabolic syndrome with insulin resistance, hypertension, and dyslipidemia. Hyperandrogenism, sleep disturbances, and many types of orthopedic complications can also develop in young children. SummaryPhysicians should not only warn obese children and their families about the long-term consequences of obesity for which they are at risk in adulthood, they should also screen for the many diseases that may already be present.

Sleep Architecture and Glucose and Insulin Homeostasis in Obese Adolescents

OBJECTIVE Sleep deprivation is associated with increased risk of adult type 2 diabetes mellitus (T2DM). It is uncertain whether sleep deprivation and/or altered sleep architecture affects glycemic regulation or insulin sensitivity or secretion. We hypothesized that in obese adolescents, sleep disturbances would associate with altered glucose and insulin homeostasis. RESEARCH DESIGN AND METHODS This cross-sectional observational study of 62 obese adolescents took place at the Clinical and Translational Research Center and Sleep Laboratory in a tertiary care children’s hospital. Subjects underwent oral glucose tolerance test (OGTT), anthropometric measurements, overnight polysomnography, and frequently sampled intravenous glucose tolerance test (FSIGT). Hemoglobin A1c (HbA1c) and serial insulin and glucose levels were obtained, indices of insulin sensitivity and secretion were calculated, and sleep architecture was assessed. Correlation and regression analyses were performed to assess the association of total sleep and sleep stages with measures of insulin and glucose homeostasis, adjusted for confounding variables. RESULTS We found significant U-shaped (quadratic) associations between sleep duration and both HbA1c and serial glucose levels on OGTT and positive associations between slow-wave sleep (N3) duration and insulin secretory measures, independent of degree of obesity, pubertal stage, sex, and obstructive sleep apnea measures. CONCLUSIONS Insufficient and excessive sleep was associated with short-term and long-term hyperglycemia in our obese adolescents. Decreased N3 was associated with decreased insulin secretion. These effects may be related, with reduced insulin secretory capacity leading to hyperglycemia. We speculate that optimizing sleep may stave off the development of T2DM in obese adolescents.

Endocrine outcome in long-term survivors of low-grade hypothalamic/chiasmatic glioma

We have evaluated the frequency of endocrine abnormalities in a large group of patients with hypothalamic/chiasmatic glioma (H/CG) and its correlation with the different forms of therapy.

Increasing Incidence of Type 1 Diabetes in Youth: Twenty years of the Philadelphia Pediatric Diabetes Registry

OBJECTIVE The purpose of this study was to describe the incidence of type 1 diabetes in children in Philadelphia from 2000–2004, compare the epidemiology to the previous three cohorts in the Philadelphia Pediatric Diabetes Registry, and, for the first time, describe the incidence of type 2 diabetes. RESEARCH DESIGN AND METHODS Diabetes cases were obtained through a retrospective population-based registry. Hospital inpatient and outpatient records were reviewed for cases of type 1 and type 2 diabetes diagnosed from 1 January 2000 to 31 December 2004. The secondary source of validation was the School District of Philadelphia. Time series analysis was used to evaluate the changing pattern of incidence over the 20-year period. RESULTS The overall age-adjusted incidence rate in 2000–2004 of 17.0 per 100,000 per year was significantly higher than that of previous cohorts, with an average yearly increase of 1.5% and an average 5-year cohort increase of 7.8% (P = 0.025). The incidence in white children (19.2 per 100,000 per year) was 48% higher than in the previous cohort. Children aged 0–4 years had a 70% higher incidence (12.2 per 100,000 per year) than the original cohort; this increase was most marked in young black children. The overall age-adjusted incidence of type 2 diabetes was 5.8 per 100,000 per year and was significantly higher in black children. CONCLUSIONS The incidence of type 1 diabetes is rising among children in Philadelphia. The incidence rate has increased by 29% since the 1985–1989 cohort. The most marked increases were among white children ages 10–14 years and black children ages 0–4 years. The incidence of type 1 diabetes is 18 times higher than that of type 2 in white children but only 1.6 times higher in black children.

Meal replacements in the treatment of adolescent obesity: a randomized controlled trial.

Use of meal replacements (MRs) in lifestyle modification programs (LMPs) for obese adults significantly increases weight loss, compared with prescription of an isocaloric conventional diet (CD). This 12‐month randomized trial examined 113 obese adolescents (mean ± s.d. age of 15.0 ± 1.3 years and BMI of 37.1 ± 5.1 kg/m2) who were assigned to a LMP, combined with meal plans of 1,300–1,500 kcal/day of CD (self‐selected foods) or MR (three SlimFast shakes, one prepackaged meal, five vegetable/fruit servings). After month 4 (phase 1), participants originally treated with MR were unmasked to their phase 2 (months 5–12) random assignment: continued use of MR (i.e., MR+MR) or transitioned to CD (i.e., MR+CD). Participants initially treated with CD in phase 1, continued with CD (i.e., CD). All three groups were treated for an additional 8 months (phase 2). Regression models were used to evaluate percentage change in BMI from baseline to month 4 (phase 1), months 5–12 (phase 2), and baseline to month 12. At month 4, participants assigned to MR (N = 65) achieved a mean (±s.e.) 6.3 ± 0.6% reduction in BMI, compared to a significantly (P = 0.01) smaller 3.8 ± 0.8% for CD participants (N = 37). In phase 2, BMI increased significantly (P < 0.001) in all three conditions, resulting in no significant (P = 0.39) differences between groups in percentage change in BMI at month 12. Across groups, mean reduction in BMI from baseline to month 12 was 3.4 ± 0.7% (P < 0.01). Use of MR significantly improved short‐term weight loss, compared with CD, but its continued use did not improve maintenance of lost weight.

Depressive Symptoms and Quality of Life in Adolescents With Type 2 Diabetes Baseline data from the TODAY study

OBJECTIVE The study objective was to examine the prevalence of depressive symptoms and relationships to quality of life and demographics in the Treatment Options for Type 2 Diabetes in Adolescents and Youth (TODAY) study’s large, ethnically diverse youth with type 2 diabetes. RESEARCH DESIGN AND METHODS A total of 704 youth with type 2 diabetes <2 years’ duration, aged 10–17 years, and BMI ≥85th percentile completed depressive symptoms and quality of life measures. RESULTS Some 14.8% reported clinically significant depressive symptoms, and older girls had significantly higher rates than older boys. CONCLUSIONS Rates of significant depressive symptoms were similar to those of healthy adolescents and lower than those of teens with type 1 diabetes. Elevated depressive symptoms, particularly in older girls, suggest clinicians assess vulnerability.

Neuropsychiatric disorders at the presentation of type 2 diabetes mellitus in children

Objectives:  To estimate the frequency of neuropsychiatric disease (NPD) in an urban pediatric type 2 diabetes mellitus (T2DM) population, to compare demographic characteristics of affected patients with those unaffected with NPD, and to determine the frequency of psychotropic medication treatment.

Hyperglycemic hyperosmolar non-ketotic syndrome in children with type 2 diabetes*.

Objective:  Hyperglycemic hyperosmolar non‐ketotic (HHNK) syndrome is thought to be a rare entity in the pediatric population, associated with significant mortality based on case reports in the literature. As obesity and type 2 diabetes in childhood grow in prevalence, such related complications may also increase. This study will serve to provide updated information regarding typical clinical course and sequelae of HHNK syndrome in childhood.